{
  "name": "InitVisitor",
  "main": {
    "name": "InitVisitor",
    "namespace": "sofa::simulation",
    "module": "Sofa.framework.Simulation.Core",
    "include": "sofa/simulation/InitVisitor.h",
    "doc": "Initialize a newly created (or modified) scene graph.\n    Forward: simulation::Node::initialize() This method puts the OdeSolver, if any, first in the list of components. Then BaseObject::init() for all components.\n    Backward: OdeSolver::bwdInit()",
    "inherits": [
      "Visitor"
    ],
    "templates": [],
    "data_fields": [],
    "links": [],
    "methods": [
      {
        "name": "processNodeTopDown",
        "return_type": "Result",
        "params": [
          {
            "name": "node",
            "type": "simulation::Node *"
          }
        ],
        "is_virtual": true,
        "is_pure_virtual": false,
        "is_static": false,
        "access": "public"
      },
      {
        "name": "processNodeBottomUp",
        "return_type": "void",
        "params": [
          {
            "name": "node",
            "type": "simulation::Node *"
          }
        ],
        "is_virtual": true,
        "is_pure_virtual": false,
        "is_static": false,
        "access": "public"
      },
      {
        "name": "isThreadSafe",
        "return_type": "bool",
        "params": [],
        "is_virtual": true,
        "is_pure_virtual": false,
        "is_static": false,
        "access": "public"
      },
      {
        "name": "getCategoryName",
        "return_type": "const char *",
        "params": [],
        "is_virtual": true,
        "is_pure_virtual": false,
        "is_static": false,
        "access": "public"
      }
    ]
  },
  "desc": {
    "description": "The `InitVisitor` is a core component in the SOFA framework, responsible for initializing a newly created or modified scene graph. It inherits from the `Visitor` class and implements methods to process nodes top-down (`processNodeTopDown`) and bottom-up (`processNodeBottomUp`). During initialization, it calls `simulation::Node::initialize()` which ensures that the OdeSolver (if present) is processed first, followed by invoking `BaseObject::init()` for all components. In the backward pass (`bwdInit`), it handles any post-initialization steps required by specific components.\n\nThe component interacts with other SOFA components such as `Node`, which contains a list of objects to be initialized, and mechanical models that need bounding box updates. The initialization process ensures proper setup for simulation nodes and their associated objects before the simulation begins. It also provides methods to indicate whether it is thread-safe (`isThreadSafe`) and to retrieve its category name (`getCategoryName`)."
  },
  "maths": {
    "maths": "The `InitVisitor` component in the SOFA framework is responsible for initializing the scene graph, which encompasses all mechanical objects and their interactions. It does not directly contribute to any governing equations or operators such as mass matrix \\(M\\), stiffness matrix \\(K\\), internal force \\(f_{int}\\), residual \\(R\\), etc., but it ensures that these components are properly set up before the simulation begins.\n\n### Role in the FEM Pipeline\nThe `InitVisitor` operates during the initialization phase of a newly created or modified scene graph. Its primary tasks include:\n\n1. **Forward Pass (`processNodeTopDown`)**: This method calls `simulation::Node::initialize()` for each node, which ensures that the OdeSolver (if any) is processed first in the list of components. It then invokes `BaseObject::init()` on all components within the node.\n\n2. **Backward Pass (`processNodeBottomUp`)**: This method processes nodes in reverse order and calls `bwdInit()` for each component to handle post-initialization steps.\n\n### Numerical Methods and Discretization Choices\nThe `InitVisitor` itself does not encode any specific numerical methods or discretization choices. Instead, it ensures that the necessary initialization steps are performed so that subsequent simulation steps can proceed correctly. This includes setting up bounding boxes for visual models and ensuring that all components are properly initialized.\n\n### Broad Variational/Lagrangian Mechanics Framework\nThe `InitVisitor` is a critical component in the broader variational and Lagrangian mechanics framework implemented by SOFA. It ensures that all mechanical objects and their interactions are correctly set up before entering the simulation loop, where governing equations such as the weak form of the Euler-Lagrange equations or the balance laws of continuum mechanics are solved.\n\n### Summary\n- **Governing Equations**: The `InitVisitor` does not directly implement any governing equations; it ensures that all necessary components and their interactions are properly initialized.\n- **Constitutive Laws**: No constitutive laws are involved in this component.\n- **Kinematic Laws**: No kinematic laws are directly implemented by the `InitVisitor`. It prepares the scene graph for subsequent simulation steps where these laws may be applied.\n- **Role in FEM Pipeline**: The `InitVisitor` operates during the initialization phase, ensuring proper setup of mechanical objects and their interactions before the simulation begins.\n\nOverall, while the `InitVisitor` does not directly contribute to mathematical formulations, it is essential for setting up the scene graph correctly, which is a prerequisite for any subsequent numerical simulations."
  },
  "summary": {
    "abstract": "`InitVisitor` initializes a newly created or modified SOFA scene graph, ensuring proper setup of mechanical objects and their interactions before simulation.",
    "sheet": "\n# InitVisitor\n\n## Overview\n\nThe `InitVisitor` is a core component in the SOFA framework responsible for initializing newly created or modified scene graphs. It ensures that all components within each node are properly initialized by calling `BaseObject::init()` on them and handling any post-initialization steps required by specific components.\n\n## Practical Notes\n\nDuring initialization, `InitVisitor` places the OdeSolver (if present) first in the list of components to be processed. It also ensures that bounding boxes for visual models are updated correctly. Practitioners should ensure that all necessary components and their interactions are properly set up before invoking this visitor to avoid runtime errors or incorrect simulation behavior."
  }
}